Last slip for removing shoes from lasts



atented or. 3, less UETED 'i [11 LAST SLIP FOR REMOVING SHOES FROM LASTS John C. Eldridge, Bridgewater, and Francis A. Flaherty, Boston, Mass, assignors to United Shoe Machinery Corporation, Flemington, N. J., a corporation of New Jersey No Drawing. Application March 11, 1950, Serial No. 149,217

4 Claims.

This invention relates to the removal of shoes from lasts and particularly to a new last slip particularly adapted to aid in the removal of unlined shoes from lasts.

Shoes are given the desired shape by stretching the upper portions around lasts, and hence the upper portions conform closely to all irregularities of the last. The clos engagement between the shoe and the last makes it difficult to remove the shoe from the last since the combination of resilient pressure of the shoe against the last and the irregularities in the shoe and in the last resist slipping of the shoe over the last. This problem has been met heretofore by use of last slips adapted to smooth the surface of the last and which heretofore have involved a dust or a hard smooth waxy coating applied to the last.

The increasing production of unlined shoes has introduced last removal problems more cult than those heretofore encountered. The unlined shoe does not have fabric or other relatively smooth and regular interior surface to r..- duce the tendency of the shoe to seize onto the last. A further very serious difiiculty arises when a toe stiilener is employed in the shoe. Toe stiffeners particularly for unlined shoes necessarily possess adhesive properties to bond them to adjacent surfaces of the shoe uppers. While it is endeavored to restrict this adhesive to the surface of the stiffener which contacts the shoe upper, it is almost inevitable that some of the adhesive material reaches the exposed surface of the stiffener and tends to bond the stiffener to the last. It has been found that conventional last slips do not prevent sticking of shoes to lasts under these conditions.

It is a feature of the present invention to provide a new last slip which provides for easier removal of shoes from lasts and which prevents sticking of unlined shoes to lasts.

It is a further feature to provide a last slip for forming a pellicle for a last which possesses unique physical properties especially adapting it to prevent penetration of adhesive from a shoe stiffener to a last and possessing a character which facilitates movement of the relatively rough interior of an unlined shoe with respect to a last surface.

The last slip of the present invention is an aqueous composition adapted to deposit on a last a pulpy film or pellicle comprising a waxy material and a high proportion relative to the wax of platelets of mica. In this pulpy film or pellicle the mica disrupts the continuity of the wax and permits portions of the pellicle to slip readily with respect to other portions. In contrast to the coating formed by known last slips, the pellicle deposited by the last slip of the present invention shears within itself when a shoe is removed from a last covered by the pellicle, and does not merely provide a glossy surface over which the inner surface of the shoe must slide when the shoe is removed from the last.

The last slip of the present invention which forms this pulpy film or pellicle is a brushable fluid mixture of an aqueous wax emulsion and an aqueous dispersion of mica. It is important that the emulsion and dispersion be combined in appropriate relativ proportions to give a composition in which the ratio of mica to wax is in a high range not heretofore contemplated for last slip compositions, i. e. a range of from 4 /2 to '7 parts by weight of mica to two parts by weight of wax. It is likewise important to employ a relatively high solids content wax emulsion and mica dispersion to provide a solids content in the final mixture of from 30% to by weight based on the weight of the mixture. This high solids content comprising mica and wax in these relative proportions insures that mica and wax are deposited as a thick film or pellicle with the mica platelets disposed to disrupt the continuity of the deposited wax, and gives a film or pellicle which is readily sheared in removal of a shoe, but does not crumble or powder objectionably on handling.

The mic-a dispersion constituting one component of the slast slip comprises from 35% to 40% by weight of finely divided, e. g. 200 mesh, mica based on the weight of the ultimate dispersion, an an aqueous solution of a dispersing agent. Suitable dispersing agents include synthetic dispersing agents e. g. sodium salts of alkyl aryl sulfom'c acids, and soaps, e. g. the reaction products of the higher fatty acids with nitrogen base organic alkalis such as triethanolamine, diethanolamine, diethyl amine and other alkyl amines and morpholine. Ordinarily from 2% to 3 /2% by weight of the soap based on the weight of the ultimate dispersion is sufiicient.

The special wax emulsion may be prepared by combining a water-insoluble wax melting in the range of from 45 C. to 70 C. in molten condition with an emulsifying agent and water. Ordinary paraflin wax obtained from petroleum and having a melting point in the range of 45 C. to 70 0., preferably C. has been found very satisfactory. Other waxes which have been found useful are glyceryl monosterate and ethylene glycol monostearate. An emulsifier known as Emulsifier RB made by Lukon, Inc. of Leominister, Massachusetts, which has been found most satisfactory for the dispersion of paraffin wax is a waxy solid at room temperatures and is understood to be an anionic emulsifier comprising the sodium salt of a sulfonated petroleum product having long inactive carbon chains. Other anionic emulsifiers may be used. The wax and emulsifier are employed in the ratio of from 3 to 8 parts by weight of the wax to one part by weight of the emulsifier, and are combined with sufiicient water to form a wax emulsion containing from to by weight solids. The water in which the wax is dispersed to form the new Wax emulsion may contain a bodying agent such as sodium carboxy methyl cellulose, sodium alginate (Keltex), methyl cellulose, gum tragacanth or other water soluble gum to increase the thickness or body of the ultimate product if desired. Ordinarily, /4 of 1% by weight of the bodying agent or thickener based on the weight of the wax emulsion will be adequate but more or less may be used to give a thicker or thinner product if desired.

The wax emulsion and mica dispersion are mixed together to form a thick, milky fluid having a solids content of from 30 to 50% by weight of which the wax and mica constitute from 85 to 90% by weight. The last slip is readily applied to a last as by brushing and forms a relatively thick coating. This coating dries to an opaque v pulpy film or pellicle comprising the Wax with a high proportion of mica platelets uniformly distributed through the film or pellicle. The dried coating possesses sufficient strength so that a shoe upper can be positioned thereon and various shoemaking operations performed without displacing the coating or pellicle from its position between the last and the interior of the shoe. In the making of unlined shoes wherein toe portions are provided with a stiffener, for example with a solvent softened pyroxylin type box toe stiffener, this coating eifectively prevents the pyroxylin from bonding to the last.

When the shoe is stripped from the last the film or pellicle gives way or shears within the film or pellicle. The platelike mica particles apparently break up the continuity of the waxy structure and permit portions of the film to slip with respect to other portions. Rough surfaces on the interior of the shoe to be removed do not have to slide since slipping occurs within the film or pellicle.

The following examples of last slips are given for purposes of illustration only to aid in understanding the invention and it is to be understood that the invention is not restricted to the specific proportions, materials or operational details described therein.

Example I .-155 lbs. of a parafiin wax derived from petroleum and having a melting point of C. was melted by heating to a temperature of from 73 C. to 75 C. and to 25 lbs. of an anionic sulfonated petroleum derivative wetting agent (Emulsifier RB) was added thereto. 23.75 gal. of water containing 12 oz. of sodium carboxy methyl cellulose were then combined with the molten wax material and the mixture thoroughly agitated to secure uniform distribution and thorough emulsification of the waxy material in the water. The emulsion was then diluted by addition of water to make 50 gal.

165 lbs. of 200 mesh mica were added to 28 gal. of water and thoroughly dispersed in the solution using 11 lbs. of triethanolamine oleate as a dispersion agent. The dispersion was then diluted with water to a solids content of 42.2%.

The wax emulsion and the mica dispersion were then combined in proportions to provide a ratio of mica to wax of 4.5 to 2 and thoroughly mixed together to form a relatively thick but brushable whitish fluid constituting the last slip. The last slip was brushed on the toe portion of a last and permitted to dry. The dried coating formed an opaque whitish film or pellicle. An unlined shoe upper with a solvent-softened pyroxylin box toe stiffener was positioned on the last and shoemaking operations were carried out resulting in a completed shoe. This shoe was readily stripped from the last and gave no evidence of sticking. On observation of the last after removal of the shoe, it was observed that a substantial portion of the area covered by the last slip still retained material adhering thereto but that in large areas, the film or pellicle was reduced in thickness by the shearing action which occurred during the removal of the shoe.

Example II .-l1 lbs. of the sodium salt of lauryl sulfate (Orvus, W. A.) was dissolved in 14 gal. of water at a temperature of about 55 to 65 C. 125 lbs. of ethylene glycol monostearate was melted and heated to a temperature of to C. The solution of the sodium salt of lauryl sulfate was then combined with the molten ethylene glycol monostearate and thoroughly agitated to form a uniform emulsion. This emulsion was diluted with hot Water to gal.

'7 lbs. 8 oz. of a dispersing agent, understood to be the sodium salt of polymerized alkyl aryl sulphonic acids (Darvan #1) was dissolved in 7 gal. 36 fiuid oz. of water heated to a temperature of from 55 to 65 C. 9 gal. fluid oz. of cold water were then added to the solution. To the resulting solution there were added lbs. of 200 mesh mica and the mixture agitated to effect a thorough dispersion. This dispersion was diluted with Water to form 60 gal. The mica dispersion was then combined with 36 gal. 64 oz. of the emulsion of ethylene glycol monostearate and the two were thoroughl mixed together to form a relatively thick but brushable whitish fiuid constituting a last slip. This last slip was employed in the same manner as the last slip of Example I. An unlined shoe formed on a last coated with this last slip was readily stripped from the last and gave no evidence of sticking. The film or pellicle deposited by this last slip Was somewhat harder than the pellicle deposited by the first last slip though still pulpy.

Having described our invention, what we claim as new and desire to secure by Letters Patent 0:" the United States is:

1. A last slip adapted to form, when applied to a last and dried, a pulpy coating having low resistance to shear, said last slip comprising a thick, brushable fiuid, high solids content blend of a dispersion of finely divided mica in an aqueous medium and an aqueous emulsion of a waterinsoluble wax melting in the range of 45 C. to 70 0., said mica and Wax being present in the ratio of from as to 7.0 parts by weight of mica to 2 parts by weight of wax.

2. A last slip adapted to form, when applied to a last and dried, a pulpy coating having low resistance to shear, said last slip comprising a blend of a dispersion of finely divided mica in an aqueous medium and an aqueous emulsion of a water-insoluble wax melting in the range of 45 C. to 70 C., said last slip having a solids content of from 30 to 50%, and said mica and wax being present in the ratio of from 4.5 to

7.0 parts by weight of mica to 2 parts by weight of wax.

3. A last slip adapted to form, when applied to a. last and dried, a pulpy coating having low resistance to shear comprising a blend of a dispersion containing from 35% to 40% by weight of finely divided mica in an aqueous medium with an aqueous emulsion of paraflin wax comprising from 35% to 50% by weight of a mixture of parafiin wax having a melting point of from 45 to 70 C. and a waxy solid anionic sulfonated petroleum derivative wetting agent in the ratio of from 3 to 8 parts by weight of the wax to one part by weight of the wetting agent, said mica dispersion and wax emulsion being combined in relative proportions to give a ratio of from 4.5 to 7.0 parts by weight of mica to 2 parts by weight of wax.

4. A last slip adapted to form when applied to a last and dried a pulpy coating having low resistance to shear comprising a blend of a dispersion containing from to by weight of finely divided mica in an aqueous medium, with an aqueous emulsion of ethylene glycol monostearate comprising from 35% to of ethylene glycol monostearate and the sodium salt of lauryl sulfate in the ratio of from 3 to 8 parts by Weight of the ethylene glycol monostearate to one part by weight of the sodium salt of lauryl sulfate, said mica dispersion and said ethylene glycol monostearate emulsion being combined in relative proportions to give a ratio of from 4.5 to 7.0 parts by weight of mica to 2 parts by weight of ethylene glycol monostearate.

JOHN C. EIDRIDGE.

FRANCIS A. FLAHERTY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,378,521 Warth et a1. June 19, 1945 2,581,407 Hain Jan. 8, 1952 

1. A LAST SLIP ADAPTED TO FORM, WHEN APPLIED TO A LAST AND DRIED, A PULPY COATING HAVING LOW RESISTANCE TO SHEAR, SAID LAST SLIP COMPRISING A THICK BRUSHABLE FLUID, HIGH SOLIDS CONTENT BLEND OF A DISPERSION OF FINELY DIVIDED MICA IN A AQUEOUS MEDIUM AND AN AQUEOUS EMULSION OF A WATERINSOLUBLE WAX MELTING IN THE RANGE OF 45* C. TO 70* C., SAID MICA AND WAX BEING PRESENT IN THE RATIO OF FROM 4.5 TO 7.0 PARTS BY WEIGHT OF MICA TO 2 PARTS BY WEIGHT OF WAX. 